Foam stabilizer



- Patented Nov. 24, 1925.

UNITED STATES PATENT OFFICE NATHANIEL T. EWER, F SWARTHMORE,PENNSYLVANIA, ASSIGNOR, BY MESNE AS- SIGNMENTS, TO AMDYCO CORPORATION, ACORPORATION OF NEW YORK.

FOAM STABILIZER.

. No Drawing. Original application filed December 18, 1923, Serial No.681,429. Divided and this application filed September 18, 1924. SerialNo. 738,557.

To all whom it may concern:

Be it known that I, NATHANIEL T. EWER, a citizen of the United States,residing at Swarthmore, in the county of Delaware,

State of Pennsylvania, have invented certain new and useful Improvementsin Foam Stabilizers; and I do hereby declare the following to be afull,clear, and exact description of the invention, such as will enableothers skilled in the art to which it appertains to make and use thesame.

This invention relates to foam stabilizers particularly adapted for usein solutions which, when mixed, are capable of forming foam blankets forthe purpose of extinguishing fires. The invention relates moreparticularly to foam stabilizers produced from 1 relatively inexpensivewaste materials, and

the present application is a division ofmy s copending applicatiomSerial No. 681,429,

filed December 18, 1923.

It is to be understood that the use of foam blankets forfire-extinguishing purposes has been practiced for many years. Toproduce these blankets solutions capable of releasing a gas, such ascarbon dioxide, and containing the stabilizer, are mixed at or adjacentto the fire and the mass of bubbles produced by the reaction is appliedto the fire to shut off the supply of oxygen therefrom. The function ofthe stabilizer is to increase the toughness and tenacity of the foam sothat it will effectively accomplish the desired result. The solutionsused contain generally sodium bicarbonate and aluminum sulphaterespectively, the foam stabilizer being mixed usually with the sodiumbicarbonate solution.

The stabilizer heretofore commonly used in firesextinguishing solutionsfor the purpose of producing foam blankets is an extract of licoriceroot which gives to the foam the desired toughness and tenacity andensures the successful accomplishment of its intended purpose. Manysuggestions have been made heretofore regarding the substitution ofother foam stabilizers such as black liquor from the manufacture ofpaper pulp, glue, saponin, etc., for the extract of licorice root. Thesubstitutes have not proved to be effective or are less satisfactorythan extract of licorice root which has been employed almost exclusivelyas a foam stabilizer in fireextinguishing compositions.

It is the object of the present invention to provide a foam stabilizerwhich is relatively inexpensive and is equal to or more effective thanthe extract of licorice root heretofore used.

Other objects and advantages of the invention will be apparent as it isbetter understood by reference to the following specification.

My research has disclosed a source of material suitable for use as afoam stabilizer having all of the desirable properties of materialsheretofore suggested for that purpose and being derived preferably froma waste product so that the cost thereof is reduced to a minimum. I havediscovered that certain barks when suitably extracted Provide a verysatisfactory foam stabilizer and that the stabilizer may be usedadvantageously in connection with fire-extinguishing solutions for thepurpose of providing a tough and tenacious foam blanket.

Although the product may be prepared from the barksin their originalcondition, it is preferable to firstextract the barks and therebyrecover valuable products which are not useful as foam stabilizers.barks which I employ are extracted for the purpose of producingcommercial products such as dye-stuffs and tannin extracts. The residualmaterial was, prior to my invention, considered as waste and wasutilized as low grade fuel. 'This waste material may be subjected to asecondary extraction under suitable conditions to separate a foamstabilizer thereform, and this extract is uti lized for the purpose ofthe invention.

In carrying out the invention I may use various oak barks, but moreparticularly chestnut oak bark .including the species Quercus Muhlenbergz'i of EngeZma/nn, Quercus Primes of Linnaeus and QuercusMichaumii of Nuttall. This bark produces, upon primary extraction withwater and steam under pressure, a valuable dye-stuff which has, however,no utility as a foam stabilizer.

When'the extracted bark is subjected to a secondary extract on the foamstabilizer is obtained. The secondary extractlon 1s pref- In fact, the30 erably conducted with a solution of an alkali such as caustic soda.About eight per cent of caustic soda figured on the weight of the drymaterial is used. The extraction is carried out under a steam pressureof ap proximately forty-five pounds .which is maintained until theextraction is sufficiently complete: that is to say. when thespecilicgravity of the liquor is about Ill-l5 or equivalent to 9 Twaddell. Twoor more hours may he required for the extraction. After the liquor isblown off from the extractor it is filtered and then evaporated.preferably in a vacuum pan. until its specific gravity is approximately1.16 equivalent to 32 Twaddell.

The extract thus obtained is quite lluid and easily runs through a twoinch opening at ordinary temperatures. It does not ferment and willprevent fermentation of substances which might otherwise undergo thischange. It is, therefore, particularly desirable for use in closedcontainers which re main at long intervals at temperatures favorable tofermentation. The extract is readily soluble in both hot and cold waterand is quickly dissolved in bicarbonate solutions such as are used infire-extinguishing compositions. These solutions. when used with theextract. show very little if any sediment after long standing. theproduct being markedly superior in this respect to foam stabilizers nowin the market.

In employing the extract for fire-extinguishing purposes. two solutionsare used. The proportions hereinafter specified are suggestive merely asthe compositions may be varied considerably.

Per cent. Bicarbonate of soda 8.5 Extract of chestnut oak bark 3 Water88.5

Solution. N 0. 3.

Aluminum sulphate 13 Water 87 These solutions are maintained in separatecontainers until the need for the fire-extinguishing blanket occurs. Thesolutions are then mixed and the chemical reaction results in theproduction of a large volume of carbon dioxide. The latter is releasedin the solution and produces a mass of bubbles which, owing to thepresence of the foam stabilizer, are extremely tough and tenacious. Whenthis foam is applied to a fire oxygen from the atmosphere is preventedsubstantially from reaching the combustible material and the fire isextinguished promptly.

As hereinbefore noted the foam stabilizer may be obtained directly byextracting the barks mentioned with alkaline solutions. In this case theextract is contaminated to a certain extent with the valuable materialswhich are ordinarily extracted with water, and to that extent the yieldof foam stabilizer would be somewhat reduced and its efficiency would belowered. It is preferable, accordingly, first to subject the bark towater extraction as described and to produce the foam stabilizer by asecondary extraction. This practice will be followed usually because theextraction of dyestuffs and tannin from the barks mentioned is anestablished industry and large quantities of bark which has beensubjected to the primary extraction are available and can'be obtained ata relatively low cost. The supply of such extracted bark is sufficientto make this material an economical and desirable source of foamstabilizer.

The foam stabilizer prepared as hereinbefore described may be utilizedadvantageously in liquid form. In this form it can be added to one orthe other of the water solutions of the fire-extinguishing composition.It is also desirable to use the foam stabilizer in a solid form so thatit can be added directly to the dry ingredients of thefire-extinguishing composition. For this purpose the liquid stabilizercan be crystallized by subjecting it to evaporation in a vacuum pan, forexample, and reducing the moisture content until the solids crystallizetherefrom. This provides a crystalline or granular material which may bemixed, for example, with the bicarbonate of soda. The mixture can bepackaged in dry form and in quantity sufiicient to furnish astandardized charge for a fire-extinguisher. Aluminum sulphate can bepackaged likewise and consequently the solutions can be prepared bymerely adding the required amount of water to the contents of thepackages.

While the extract is described moreespecially as a stabilizer forfire-extinguishing foam, it may be utilized advantageously for otherpurposes. I intend, therefore, to claim the product for all purposes towhich it 1s adapted.

Various changes may be made in the details of the method of extractionas hereinbefore described without departing from the invention orsacrificing any of the advantages set forth.

I claim:

1. A foam stabilizer consisting of an extract of chestnut oak barksubstantially free from tannin.

2. A foam stabilizer consisting of a secondary extract of chestnut oakbark.

A foam stabilizer for fire-extinguishing compositions and similarpurposes consisting of the extract obtained by subjecting chestnut oakbark to the action of an alkaline solution.

.4. A foam stabilizer for fire-extinguishing fires comprising a drygranular extract .of compositions and similar purposes consistchestnutoak bark combined with a gas rcing of a secondary extract obtained bysubleasing agent. 10 jecting chestnut oak bark'to the action of an Intestimony whereof I aflix my signa- 5 alkaline solution after a'primaryextraction ture. i

with water.

5. A composition for use in extinguishing? NATHANIEL T. EWER.

